Recent advances in the biological control of soil-borne pests and pathogens

الملخص EN

In general, two approaches have been followed to achieve biological control of soil-borne pests and pathogens: i) enhancement of the natural potential of suppression that exists in every soil, and ii) introduction of a natural or improved efficient strain of antagonistic microorganism.

Both approaches need a good knowledge of the biology and ecology of target organisms and biological control agents.

The natural or introduced population of antagonists must be target- specific, present and active at a place and a time at which the pathogen is susceptible to its antagonistic activity.

Significant advancement has been made in biochemical and molecular approaches to understand the modes of action of several biological control agents such as Trichoderma spp., fluorescent pseudomonads.

nonpathogenic Fusarium oxysporum, etc...

knowledge of the modes of action is required to: i) improve the methods of screening of potential biological control agents, ii) choose strains having different modes of action to be used in mixtures, iii) select the best conditions to produce, formulaic and apply the biological control agents.

For instance, the association of a nonpathogenic strain of F.

oxysporum competing with the pathogen for carbon with a strain of fluorescent Pseudomonas competing for iron always improved control of fusarium wilt in tomato and carnation.

To improve the long-term effect of this control, it would be interesting to add a third strain of either nonpathogenic F.

oxysporum or P.

fluorescent, able to induced systemic resistance in the plant.

The tools are now available to evaluate the diversity among natural populations of antagonistic microorganisms and study the selection pressure exerted by the plant.

These studies are important to select efficient antagonists which are competent to colonize the roots of the host plants.

This knowledge could also be useful to select disease management practices able to enhance the natural populations of biological control agents in soil.